Lighting control system

ABSTRACT

A system for providing light from an auxiliary light source only during hot start conditions of a mercury vapor lamp by sensing voltage across the mercury vapor lamp and, if that voltage exceeds 235.V, indicating that a hot start condition is present, closing contacts in circuit with the auxiliary light source. Upon striking, the voltage across the mercury vapor lamp decreases, and the circuit of the auxiliary lamp opens. In a solid state version of the system, voltage across the mercury vapor lamp is sensed by a neon tube which illuminates a photoconductor in the control circuit of a triac, which controls current to the auxiliary lamp. In a relay version, a relay coil, which closes its contacts only in response to above 225.V, is connected across the mercury vapor lamp, and has contacts connected in series with the auxiliary lamp.

United States Patent Horowitz June 17, I975 LIGHTING CONTROL SYSTEM OTHER PUBLICATIONS [75] Inventor: Victor Horowitz, Oceanside, N.Y. m in popular Electronics". VOL 30' N 5 May [73] Assignee: Current Industries, Inc., Oceanside, 1969' 8 8| &

N.Y. Primary Examiner-James W, Lawrence [22] Flled lune 1974 Assistant ExaminerE. R. LaRoche [2i] Appl. No.1 480,71] Attorney, Agent, or Firm-Hyman Hurvitz Related US. Application Data I 57] ABSTRACT [63] fgyg rsgi gi g of 371503 June A system for providing light from an auxiliary light source only during hot start conditions of a mercury us. 01. 31s 7 39; 315 91- by F "wage '9' {52] 35/93. fg gy vapor lamp and. if that voltage exceeds 235.V, indi- 340/251 cating that a hot start condition is present, closing [5]] Int CH H05B 37/04 HO'SB 41/46 contacts in circuit with the auxiliary light source. I58] Field 315/88 1 92 93 Upon striking, the voltage across the mercury vapor 3l5ll 2 l l 2 7 l29 13:1 l36 I49 p decreases. and the circuit of the auxiliary lamp 315/154 159 178 182" 34(l/248 A 2:18 C Opens. In a solid state version of the system, voltage across the mercury vapor lamp is sensed by a neon 340/251 307/39 317/124 323/21 tube which illuminates a photoconductor in the con- [56] Reerences Cited trol circuit of a triac, which controls current to the auxiliary lamp. In a relay version, a relay coil, which UNITED STATES PATENTS closes its contacts only in response to above 225V, is 3,l49 26l Aizawa connected across the mercury apor lamp and has contacts connected in series with the auxiliary lamp. UI'ISOI'I 3,694,692 9/1972 Pressman 3l5/l54 5 Claims, 2 Drawing Figures AUXlLlRRY LAMP 24 PHUTDCELL \ZOV. Ac.

PATENTEDJUN 17 ms Q .Ylgfg E x QN CCCC J :00 ZQ GN LIGHTING CONTROL SYSTEM This application is a continuation in part of Ser. No. 37 l ,503, filed June 19, I973, and entitled MERCURY VAPOR LAMP WITH AUXILIARY LIGHT SOURCE, now abandoned.

BACKGROUND OF THE INVENTION In my prior application, Ser. No. 371,503, now pending, a system was disclosed for energizing an emergency lamp during either hot start or cold start conditions of a mercury arc lamp. Hot start conditions imply that the lamp has been illuminated and is hot, but that a momentary power failure has occurred. Such an event causes the lamp to remain dark for several minutes, and then to reilluminate. On the other hand, when a lamp is, while cold, connected to a source of voltage, it immediately becomes illuminated but requires several minutes to achieve full illumination.

It is well known in the art to provide an auxiliary lamp, normally off, which provides illumination during hot start and cold start conditions, until a predetermined level of light output has been achieved by the mercury vapor lamp.

In the case of one commonly used mercury vapor lamp, during cold start, the voltage across the lamp is mutually about l5.V and builds up gradually to 135.V. During hot start conditions at least 235.V appears across the lamp initially. After several minutes the lamp restrikes and the voltage across it drops to approximately l5. volts. As illumination increases, reaching a maximum value after several minutes, the voltage across the lamp also increases to l35.V. An auxiliary lamp is desired on during both hot start and cold start conditions in some systems, for example, in the system of Ser. No. 371,503. It is often desired to provide auxiliary lighting only during hot start and not during cold start, which enables considerable simplication of the system of Ser. No. 371,503.

It is desired to provide a lighting control which turns on an auxiliary lamp during hot start conditions of a mercury vapor, or other high intensity discharge lamp (HID), for a wide range of wattages of the HID, i.e., 100, 175, 250, or 400 watts, without modifying the control. This result is achieved by the present system.

BRIEF DESCRIPTION OF THE INVENTION A hot start only control, for a HID lamp, in which voltage across the lamp is sensed, and only if above a predetermined value, connects an auxiliary lamp to a power source.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a relay circuit control for turning on an auxiliary light source during hot start conditions of a HID lamp; and

FIG. 2 is a solid state version of the system of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENTS In FIG. 1, is a HID lamp, preferably a mercury vapor lamp. For a wide range of wattage ratings, the lamp 10 has 135.V thereacross during normal operation, but about 235.V during hot start conditions. Connected across the lamp 10 is a relay coil 12, which actuates its normally open contacts 14 only in response to a voltage of at least 225.V. During normal operation contacts 14 are open. During hot start conditions the contacts close. The lamp I0 is energized from an autotransformer 16, having primary winding 18, and a secondary winding 20. Primary winding 18 is connected across a l20.VAC line 21. Secondary winding 20 is connected from one side of the line through a ballast capacitor 22 to one side of the lamp l0, and the other side of the lamp is connected directly to the other side of the line. Auxiliary lamp 24 is connected in series with relay contacts 14 directly across the line.

During normal operation, or during cold start conditions, relay coil I2 sees insufficient voltage to close its contacts 14. During hot start conditions, relay coil [2 sees sufficient voltage to close its contacts 14, energizing lamp 24, which remains energized until the arc in the mercury vapor lamp restrikes. At that time, the voltage across the mercury vapor lamp and the relay coil decreases to approximately 15. volts and the au xiliary lamp 24 is de-energized.

Referring to FIG. 2 of the accompanying drawings, a triac 30 is connected in series with lamp 24 across primary winding 18. A photoconductive cell 32 is connected in series with a phasing capacitor 34 and a phasing resistance 35 between one side of line 21 and one side of lamp 24. The phasing capacitor has one side connected to line 21a and the other side connected via diac 36 to the firing electrode of triac 30.

Connected directly across the lamp I0 is a voltage chain consisting of resistances 40 and 42, of 91 .K and 68K respectively, forming a voltage divider circuit. Although the neon lamp 44 fires at 75. volts, its placement in the voltage divider circuit necessitates that a minimum of 235. volts be impressed across lamp 10 in order that 75. volts appear across the neon lamp. This can occur only when the lamp 10 is in a hot start condition. Neon lamp 44 illuminates photoconductive cell 32.

If neon lamp 44 is dark photocell 32 is of extremely high resistance, and the voltage across capacitor 34 is of incorrect phase to fire triac 30. If the neon lamp 44 is illuminated, i.e., during hot start conditions, the voltage and phase across capacitor 34 is of correct value to fire triac 30, and auxiliary lamp 24 illuminates. The latter condition endures until lamp 10 restrikes and itself is illuminated.

I claim:

I. A circuit for energizing an auxiliary lamp only in response to hot start condition of a high intensity discharge lamp, consisting of a voltage sensing circuit connected directly across said high intensity discharge lamp, means responsive only to a voltage as sensed by said voltage sensing circuit indicating that said high intensity lamp is in hot start condition for supplying energizing current to said auxiliary lamp, and a common source of ac voltage for said lamps, wherein said voltage sensing circuit includes a resistive voltage divider connected directly across said high intensity discharge lamp, a neon lamp connected across one of the resistors of said resistive voltage divider, said resistive voltage divider having a division relation such that said neon lamp is illuminated only in response to hot start conditions of said high intensity discharge lamp, said auxiliary lamp current supplying means including a triac connected in series with said auxiliary lamp across said source of AC voltage, and means including a photocell responsive only to illumination of said neon lamp for firing said triac, said last means including a phasing capacitor and a phasing resistance connected in series with said photocell across said source of ac voltage, and means connecting a trigger circuit of said triac to an electrode of said capacitor.

2. In a system for energizing an auxiliary lamp only in response to a hot start condition of a high intensity discharge lamp, a source of ac voltage, means connecting said high intensity discharge lamp across said source of ac voltage. a resistive voltage divider circuit connected across said high intensity discharge lamp, a neon cell connected across a portion of said resistive voltage divider circuit, said portion being selected to fire said neon cell only during hot start conditions of said high intensity discharge lamp, a triac connected in series with said auxiliary lamp across said source of ac voltage, said triac having a firing electrode, a phase shifting capacitor, means including a photo-cell connected in series with said phase shifting capacitor across said source of ac voltage to provide a phase shifting circuit, means connecting said firing electrode to a point of said phase shifting circuit such that in the dark condition of said photo-cell said triac remains unfired, said neon cell being located to illuminate said photo-cell, said phase shift circuit being operative to cause firing of said triac while said photo-cell is illuminated by said neon cell.

3. The combination according to claim 2, wherein there is provided a disc connecting said firing electrode to an electrode of said capacitor 4. The combination according to claim 2, wherein said firing electrode is connected to an electrode of said capacitor.

5. The combination according to claim 4, wherein said phase shifting circuit is connected in series with said auxiliary lamp across said source of ac voltage.

* l l l 

1. A circuit for energizing an auxiliary lamp only in response to hot start condition of a high intensity discharge lamp, consisting of a voltage sensing circuit connected directly across said high intensity discharge lamp, means responsive only to a voltage as sensed by said voltage sensing circuit indicating that said high intensity lamp is in hot start condition for supplying energizing current to said auxiliary lamp, and a common source of ac voltage for said lamps, wherein said voltage sensing circuit includes a resistive voltage divider connected directly across said high intensity discharge lamp, a neon lamp connected across one of the resistors of said resistive voltage divider, said resistive voltage divider having a division relation such that said neon lamp is illuminated only in response to hot start conditions of said high intensIty discharge lamp, said auxiliary lamp current supplying means including a triac connected in series with said auxiliary lamp across said source of AC voltage, and means including a photocell responsive only to illumination of said neon lamp for firing said triac, said last means including a phasing capacitor and a phasing resistance connected in series with said photocell across said source of ac voltage, and means connecting a trigger circuit of said triac to an electrode of said capacitor.
 2. In a system for energizing an auxiliary lamp only in response to a hot start condition of a high intensity discharge lamp, a source of ac voltage, means connecting said high intensity discharge lamp across said source of ac voltage, a resistive voltage divider circuit connected across said high intensity discharge lamp, a neon cell connected across a portion of said resistive voltage divider circuit, said portion being selected to fire said neon cell only during hot start conditions of said high intensity discharge lamp, a triac connected in series with said auxiliary lamp across said source of ac voltage, said triac having a firing electrode, a phase shifting capacitor, means including a photo-cell connected in series with said phase shifting capacitor across said source of ac voltage to provide a phase shifting circuit, means connecting said firing electrode to a point of said phase shifting circuit such that in the dark condition of said photo-cell said triac remains unfired, said neon cell being located to illuminate said photo-cell, said phase shift circuit being operative to cause firing of said triac while said photo-cell is illuminated by said neon cell.
 3. The combination according to claim 2, wherein there is provided a disc connecting said firing electrode to an electrode of said capacitor.
 4. The combination according to claim 2, wherein said firing electrode is connected to an electrode of said capacitor.
 5. The combination according to claim 4, wherein said phase shifting circuit is connected in series with said auxiliary lamp across said source of ac voltage. 